Electrical arc with pool-type electrodes



March 23, 1954 p D Y ET AL 2,673,303

ELECTRICAL ARC WITH POOL-TYPE ELECTRODES Filed Jan. 21 1950 ,Bea/Z/"z'ce faansaiy fiejarey J da! Z Ca aeiana Patented Mar. 23, 1954 UNITED ST NT OFFICE;

ELECTRICAL ARC WITH POOL-TYPE.

ELECTRODES Beatrice Pearson De Lany; Miami Beach, Fla., and Paul L. Copeland, Chicago, Ill.

20 Claims.

This invention relates to a tube or other enclosed, member having a plurality of pool-type electrodes suitablefor use with alternating current electricity.

It has for one object. to provid a tube or comparable member suitable for use: in electric lighting, preferably of the fluorescent type, and to provide a general construction suitable for use with alternating current, and so to construct the electrodes as to make auxiliary heating and other auxiliary apparatus unnecessary.

Another object is to provide a device of the type indicated in which the electrodes are so constructed as to; avoidsputtering and disintegration' of any" sort which tends to darken or otherwise damage the tube and limit its life.

Another object is to providea lighting tube of the type indicated in Which are initiation is accomplished without auxiliary means outside of the tube and in which a pair of electrodes is positioned, each' electrode serving alternately as a cathode'and as an anode as th potential is reversed.

Other objects will appear from time to time in the specification and claims.

The invention is illustrated more or less diagrammatically in the accompanying drawing, wherein:

Figure 1- is a'longitudinal section through one form of the device;

Figure 2 is a sectional detail on an enlarged scale illustrating one of the electrodes;

Figure 3 is a transverse section taken at line 3-3 of Figure 2;

Figure 4 is a sectional detail similar to Figure 2 and illustrating a modified form;

Figure 5 is a sectional view similar to Figure 2 and illustrating, on a reduced scale, a further modified form.

Like parts are indicated by'like characters in the specification and drawing.

In the particular form here shown the invention comprises an envelope or housing This envelope is preferably formed of glass or other transparent or translucent material. It is made air tight and. the air is exhausted from it. An inert gas may be present within the tube ii desired. The tube is shaped to provide two downwardly directed portions 2--2. Electrical connections 3 extend into each of the portions 2 and are sealedat the point where they pass through the envelope or tube I. Apool of mercury, or other conductive metal, which remainsliquidat normal temperatures, is placed in each of the portionsv 2, as indicated at 4. The connections. 3 are-inelectrical contact with the'pools- Within the portions 2 and'in contact withthe mercury pools 4 are disc-like members 5.. These members arepreferably formed'of'refractory re;- sistance material such as carbon or. carborune dum. Each is provided with a central opening or'cavity 6 which is preferably tapered as shown, although for. some purposes a straight sided perforation or cavity within the member 5 may be formed. If the opening 6 is tapered, as shown, the taper need not' be regular and almost any shape of the openingfi may be used.

The upper surface. of the members 5' isv provided with a section or portion! which may be of copper or other metal, and, to. each of the portions '1' is connected aconductive-wir B'Which extends from one to the other; as shown-in Figure 1. The wire 8 may, if desired; have very low electrical resistance, or; if desired,,it' may have a high resistance of several hundred ohms. The upper surface of each of the member 1' is preferably coated by an insulation 9. This insulation may comprise a ceramic insulator or other insulation may be used, and, if desired, the wire 8 may also be insulated.

In the modified form of, Figure 4, the parts are the same as above described except'that instead of the wire 8. a wire I0 is used; This wire, which is connected to both of the members 1, passes outwardly through the wall of each portion 2, as at H, so that although it is connected to each of'the, members I foritsmajor; length, it is outside of thetube or envelope I.

In .the modifiediform of Figur 5', the structure of the tube is generallyithe same as that shown in Figure 1. The means for restricting the surface of the pool, 4 is, however, modified. In place of the solid restricting'member 5 of Fig ures l, 2'and 4, a funnel-like member 12 is used. This may be formed, of any desirable material. It may be glass or other insulating material. At its upperend it is in contact with, and supported by, the pool forming portion 2 of the tube I. It maybe formed, however, of semi-conducting material, or if formed ofinsulating material, its inner surface or a part. of itsinner surface may be. provided with a semi-conductive coating or a metallic, film indicated at l3 in Figure 5. To the conductive or semi-conductive,v surface of the member 12 is secured a conductor I 4 whichis normally-the-same asthe conductor i0, andthis member passes through the wall of the envelope and is sealed as-at I5.

Therestricting member of Figure 5 may be used with the conductor l4 wholly. within the envelope as is shownin Figure, l with respect to the conductor 8. In. either. form of the. device,

the member which connects the conductive portions of the two restricting parts may lie within the envelope, as shown in Figures 1 and 2, or may lie outside of the envelope, as shown in Figures 4 and 5.

The electrodes of this invention, in whatever their form, comprise, as a whole, a pool of metal which is in liquid form at operating temperature and a member which restricts the surface of the pool exposed to the interior of the envelope and an area of material in contact with the metal pool and exposed to the interior of the envelope, which material is a poor electrical conductor. The material which is a poor electrical conductor may, for example, be a thin film of metal applied to an insulating member. This is the form of Figure 5 in which the funnel-like member l2 may be of glass or other insulating material which is coated on its inner face by a thin layer 13 of metal. In the form of the other figures the material which furnishes the area of poor conductive quality is the exposed area 6 of the member 5 which has been described as being formed of carbon or carborundum which is a poor conductor.

The expression semi-conductor is used in this art today to describe materials which are relatively poor electrical conductors. Among the materials above mentioned carbon and carborundum are today properly described by the expression semi-conductors. Silicon and germanium are other presently known materials which would now be described by the expression semi-conduc tor, as that expression is presently understood.

Although we have shown an operative form of our invention, it will be recognized that many changes in the form, shape and arrangement of parts can be made without departing from the spirit of the invention, and our showing is, therefore,to be taken as, in a sense, diagrammatic.

The use and operation of this invention are as follows:

In general, the device of the present invention, in any of its forms, is intended to operate on alternating current, and, thus, each pool becomes alternately a cathode and an anode. The tube is connected to a source of alternating current and the are starts on the first half-cycle during which potential is applied to the tube. When the potential is applied to the tube, a spot is formed within the uncovered area of the pool 4 and the arc is formed almost in tantly. Although the tube of this invention is not limited to use in connection with lighting, it has pronounced advantages for that purpose, and, when so used, the

tube may be lined or otherwise may contain fluorescent or phosphore cent pigment or materials, or both, which are effected by the light which is present when the arc is in operation to give oiT visible light. The invention is not limited either to the presence of such materials or, in case they are present, to any particular materials.

When either electrode at either end of the tube function as a cathode the resistance material of the restricting member; that is to say, the material 5 or 9 or 13, both initiates the discharge of electrons and confines this discharge to the area of the cathode pool exposed within the hole or box '6 or within the interior of the funnel-like member I2. In general, the member 5, or the funnel-like members, are formed of resistance material which is semi-conductive in character and serves also as a restricting means for restricting the amount of the pool exposed to the interior of the envelope and exposed to the electron discharge. This material also forms an extension of the electrode surface.

We claim:

1. In combination, an air tight envelope formed of insulating material and substantially free from air, a pair of separated pools of metal which metal is in liquid form at operating temperature within said envelope, said envelope defining a passage from one pool to the other, electrical connections to said pools from outside said envelope, means for concentrating the electron action within said envelope upon a limited portion of the area of each pool, said means comprising members positioned one in contact with each pool, said members overlying a portion of the area of each pool and provided with passageways therethrough, each of said members having an area of electrically conductive material, and means for electrically joining together said conductive areas of said members. 7

2. In combination, an air tight envelope formed of translucent insulating material and substantially free from air, a pair of separated pools of metal which metal is in liquid form at operating temperature within said envelope, said envelope defining a passage from one pool to the other, electrical connections to said pools from outside said envelope, means for concentrating the electron action within said envelope upon a limited portion of the area of each pool, said means comprising members positioned one in contact with each pool, said members overlying a portion of the area of each pool and provided with passageways therethrough, each of said members having an area of electrically conductive material in contact therewith, and means for electrically joining together said conductive areas of said members.

3. In combination, an air tight envelope formed of insulating material and substantially free from air, a pair of separated pools of metal which metal is in liquid form at operating temperature within said envelope, said envelope defining a passage from one pool to the other, electrical connections to said pools from outside said envelope, means for concentrating the electron action within said envelope upon a limited portion of the area of each pool, said means comprising members positioned one in contact with each pool, said members overlying a portion of the area of each pool and provided with passageways therethrough, each of said members having an area of electrically conductive material, and means for electrically joining together said conductive areas of said members, said electron restricting means including material of poor electrical conducting properties exposed to the interior of the envelope.

4. In combination, an air tight envelope formed of translucent insulating material and substan tially free from air, a pair of separated pools of metal which metal is in liquid form at operating temperature within said envelope, said envelope defining a passage from one pool to the other, electrical connections to said pools from outside said envelope, means for concentrating the electron action within said envelope upon a limited portion of the area of each pool, said means comprising members positioned one in contact with each pool, said members overlying a portion of the area of each pool and provided with passageways therethrough, each of said members having an area of electrically conductive material, and. means for electrically joining together aid conductive areas of said members, said electron restricting m'eans including material of poor aev-sgsoe 5 ei'ectricalconducting properties exposed tothe interiorof the envelope;

5'. In-combination, an air tight envelope formed of translucent insulating material and substantially free from air, apair of separated pools of metal which metal is in liquid form at operating temperature within said envelope, electrical connections to said poolsfrom outside said envelope, said envelope defining a passage from one'pool to the" other, means for concentrating the electron action within said envelope upon a limited portion of the area of each pool, said means comprising members positioned one in contact with each pool, said members overlying a portion of the area of each pool and provided with passageways therethrough, said passageways being of varying cross section and having their greatest area at a point away from the surface of a pool, each of said members having an area of electrically conductive material in contact therewith, and means for electrically joining together said conductive areas of 'said members, said electron restrictingmeans including material of poor electrical conducting properties exposed to the interior of the envelope.

6'. In combination, an air tight envelope formed of translucent insulating material and substantiallyfree from air and containing an inert gas, a pair of separated pools of metal which metal is in liquid form at operating temperature within said envelope, said envelope defining a passage from'one pool to the other, electricalconnections to said pools from outside said envelope, means for concentrating the electron action within said envelope upon a limited portion of the area of '7. In-combination, anair tight envelopeformed of translucent insulating material and substantially free from air, a pair of separated pools of metal which metal is inliquid format operating temperature within said envelope,- said envelope defining a passage from one pool to theother,

.electrical connectionsto saidpools from'outsid'e said envelope, means for concentrating-the electron action within said envelopeupon a limited portion'ofjthearea of each pool, said meanscomprising members positioned one in contact with eachpool, said members overlying a portionof the area of each pool and providedwith' passageways therethrough, each of said members carrying an area of electrically conductivematerial, and means for electrically-connecting said conductive areasof said members, the exposed surface of'said conductive areas and of said joining meansbeing covered with insulating material.

8. In combination, an air tight envelopeformed or translucent insulating material and substantially free from air and containing aninert gas, a pair of separated pools of metal which metalis in liquid form atoperatingtemperature within said envelope, said envelope defining a passage from one pool to the other, electricalconnections to said pools from outside said envelope, means for concentrating the electron action within said envelope upon a limited portion of the area of each pool, said means comprising members positi'oned one'in contact with each; pool, said menibers overlying a portion of the area of each pool and provided with passageways therethrough, each of said members carrying on itsupper surface anarea of electrically conductive material, and means for electrically connecting said conductive areas of said members, the: exposed surface of said conductive areas being covered with insulating material.

9'. In combination, an airtight envelope formed of translucent insulating material and substan.-- tially free from air, a pair of separated pools of metal which metal is in liquid form at operating temperature within said: envelope, said envelope defining a passage from one pool to the other, electrical connectionsito said pools fromoutside said envelope, means for concentrating the electron action within said envelope upon a limited portion of the areaof each pool, said means comprising members positioned one in contact with each pool, said members overlying a portion of the area of eachpooland provided with passageways therethrough, each of said members supporting on its upper surface an. area of electrically conductive material, and means positioned within said envelope for electrically connecting said conductive areas of said members, the exposed surface of saidconductive areas and of: said joining means being covered with insulatingmaterial.

10. In combination, an air tight envelope formed of translucent insulating material and substantially free from air; a pair of separated pools of metal which metal is-in liquid form at operating temperature; within said envelope, said envelope defining a passage from one poolto the other; electrical connections to said pools from outside said envelope, means for concentrating the electron actionwithin said envelope upon a limited portion of the area of each pool, said means comprising: members positioned one in contact with each. pool, said members overlying a portion of: the area of" each pool and provided with passageways therethrough, said passageways being of varying cross section and having their greatest area at a point away from the surface of a' pool, each of said members provided in contact with its upper surface with an area of electrically conductive material, and means positioned withinsaid envelope for electrically connecting said conductive areas of said members, the exposed'surface ofsaid conductive areas and of said joining means being covered with insulating material, said. electron. restrictin means being formedof: semi-conductive material.

Il. In combination in an electrical discharge tube, an. air tight envelope substantially. free from: air, said envelope being formed of translucent material and shaped to provide a pluraiity oifpool retaining portions, pools of metal, whichis fluid at normal operating temperature, in each ofjsaid retaining portions, said envelope defining a passage from one pool to-the other, means for restricting the exposed area of. said pools comprising members, one in contact with each pool, said members being provided with openings therethrough of an area lessthan the total-ar aot' apool, an area of highly conductive metallic. material positionedupon and in contact with said members, and. electrical. conducting means joining conductive areas.

12. Incombination in. an electrical. discharge tube,.an air tight envelope. substantially free from air, said. envelope being formed of" translucent material and" shaped" to" provide a plurality" of pool retaining portions, pools of metal, which is fluid at normal operating temperature, in each of said retaining portions, said envelope defining a passage from one pool to the other, means for restricting the exposed area of said pools comprising members, one in contact with each pool and sealed to said envelope, said members being provided with openings therethrough of an area less than the total area of a pool, an area of highly conductive metallic material positioned upon and in contact with said members, and electrical conducting means joining said conductive areas.

13.'In combination in an electrical discharge tube, an air tight envelope substantially free from air, said envelope being formed of translucent material and shaped to provide a plurality of pool retaining portions, pools of metal, which is fluid at normal operating temperature, in each of said retaining portions, said envelope defining a passage from one pool to the other, means for restricting the exposed area of said pools comprisi'ng members, one in contact with each pool,

said members being provided with openings therethrough of an area less than the total area of a pool, said openings havin their maximum diameter away from the pool, an area of highly conductive metallic material positioned upon and in contact with said members, electrical conducting means joining said conductive areas, and insulation positioned upon the exposed surfaces of said conductive areas and upon the exposed surface of said joining means.

14. In combination inan electrical discharge tube, an air tight envelope substantially free from air, said'envelope being formed of translucent material and shaped to provide a plurality of pool retaining portions, pools of metal, which is fluid at normal operating temperature, in each of said retaining portions, said envelope defining a passage from one pool to the other, means for restricting the exposed area of said pools comprising members, one in contact with each pool and sealed to said envelope, said members being formed of semi-conducting material, said members being provided with openings therethrough of an area less than the total area of a pool, said openings having their maximum diameter away from the pool, an area of highly conductive metallic material positioned upon said members, electrical conducting means positioned within said envelope joining said conductive areas, and insulation positioned upon the exposed surfaces of said conductive areas and upon the exposed surface of said joining means.

15. In combination, an air tight envelope formed of translucent material and shaped to provide a pair of pool forming depressions, a pool ing positioned in contact with their respective :pools of metal, each of said restricting members provided with a tapered perforation having its greatest diameter at the point farthest from the surface of the pool, the upper surface of said restricting members having fixed in contact therewith a portion of electrically conductive metal,

,and an electrical conductor connected to each of said portions of conductive metalv and joining them, the exposed surface of said conductive metal being coated with electrically insulating material and said joining conductor being coated with electrically insulating material.

16. In combination, an air tight envelope formed of translucent material and shaped to provide a pair of pool forming depressions, a pool of metal, which remains liquid at operating temperature, within each of said depressions, said envelope defining a passage from one pool to the other, electric conductors extending through said envelope, onein contact with each of said pools, a pool surface restricting member positioned in each of said depressions, said members being formed of a semi-conductive material and being positioned in contact with their respective pools of metal, each of said restricting members provided with a tapered perforation having its greatest diameter at the point farthest from the surface of the pool, the upper surface of said restricting members having fixed in contact therewith a portion of electrically conductive metal, and an electrical conductor connected to each of said portions of conductive metal and joining them, said conductor being positioned within said envelope, the exposed surface of said conductive metal being coated with electrically insulating material and said joining conductor being coated with electrically insulating material.

1'7. In combination, an air tight envelope formed of insulating material and substantially free from air, a pair of separated pools of metal which metal is in liquid form at the normal operating temperature within said envelope, said envelope defining a passage from one pool to the other, electrical connections to said pools from outside said envelope, and means for concentrating the electron action upon a limited portion of the area of each pool, said means comprising members positioned one in contact with each pool, said members overlying a portion of the area of each pool and provided with passageways therethrough, each of said members having an area of electrically conductive material thereon, said conductive material of each area being connected to a metal wire which is in part outside of and sealed through the wall of the envelope.

18. In combination in an electrical discharge tube, an air tight envelope substantially free from air, and containing an inert gas at a pressure of several hundred microns or even more, said envelope being formed of translucent material and shaped to provide a pair of pool retaining portions, pools of metal, which is fluid at normal operating temperature, in each of said retaining portions, said envelope defining a passage from one pool to the other, means for restricting the exposed area of said pools comprising semi-conducting members, one in contact with each pool, said members being provided with openings therethrough of an area less than the total area of the pool, an area of metal coated on the said semi-conducting members, and electrical conducting means connecting said conducting areas.

19. In combination, an air tight envelope formed of insulating material and substantially free from air, an inert gas at a pressure of several hundred microns or even more, a pair of separated pools of metal, which metal is in liquid form at the operating temperature within said envelope, said envelope defining a passage from one pool to the other, electrical connections to said pools from outside said envelope, means for concentrating the electron action within said envelope upon a limited portion of the area of each pool, said means comprising funnel-shaped members of semi-conducting material, one for each pool, the large end of said funnel in contact with the wall and the small end in contact with its pool, a portion of the large end of each semi-conducting funnel being coated with a metal, a wire connected to each conducting area lying in part outside of and being sealed through the envelope.

20. In combination, an envelope of insulating translucent material substantially free from air and shaped to define a plurality of pool retaining parts, a pool of metal which is liquid at the operating temperature in each of said parts, conductors extending through said envelope, one in contact with each of said pools, said envelope defining a passage from one pool to the other, means for concentrating the electron action within said envelope upon a limited portion of the area of each pool, said means comprising members positioned one in contact with each pool, said members overlying a portion of the area of each pool and provided with passageways therethrough, each of said members provided with an area of electrically conductive material thereon, electrically conductive means joining together the conductive areas of each of said members, the passageways being so designed that the currents circulating in the electrical network, which is made up of the pools and all interconnections, will produce a potential distribution favorable to the establishment of an electric arc in one or more channels within said envelope.

BEATRICE PEARSON DE LANY.

PAUL L. COPELAND.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 803,836 Lunt Nov. '7, 1905 1,178,542 Skaupy Apr. 11, 1916 1,889,079 Sperti Nov. 29, 1932 2,006,466 Ludwig July 2, 1935 2,020,736 Pirani et a1 Nov. 12, 1935 2,157,923 Slepian May 9, 1939 2,160,583 Cage May 30, 1939 2,215,804 West Sept. 24, 1940 2,218,386 Smith Oct. 15, 1940 2,495,831 Warmoltz Jan. 31, 1950 FOREIGN PATENTS Number Country Date 461,380 Germany June 22, 1928 59,321 Netherlands Apr. 15, 1947 

